Which of the following benefaction process is used for the mineral Al2O3⋅2H2O?

Bauxite usually contains silica, iron oxide, and titanium oxide as impurities. In the process of leaching, alumina is concentrated by digesting the powdered ore with a concentrated solution of NaOH at 473-523K and 35-36 bar. Under these conditions, alumina dissolves as sodium silicate leaving the impurities behin